From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-f199.google.com (mail-yw0-f199.google.com [209.85.211.199]) by ozlabs.org (Postfix) with ESMTP id BAE2BB7BF4 for ; Wed, 11 Nov 2009 09:07:54 +1100 (EST) Received: by ywh37 with SMTP id 37so483572ywh.17 for ; Tue, 10 Nov 2009 14:07:52 -0800 (PST) MIME-Version: 1.0 Sender: glikely@secretlab.ca In-Reply-To: <1257882057.14374.1@antares> References: <1257882057.14374.1@antares> From: Grant Likely Date: Tue, 10 Nov 2009 14:02:58 -0700 Message-ID: Subject: Re: [PATCH 1/3] mpc52xx/wdt: OF property to enable the WDT on boot To: =?ISO-8859-1?Q?Albrecht_Dre=DF?= Content-Type: text/plain; charset=ISO-8859-1 Cc: Linux PPC Development , devicetree-discuss@lists.ozlabs.org, Wim Van Sebroeck List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Nov 10, 2009 at 12:40 PM, Albrecht Dre=DF = wrote: > Add the "wdt,on-boot" OF property as to reserve a GPT as WDT which may be= a > requirement in safety-related (e.g. ISO 61508) applications. > > Signed-off-by: Albrecht Dre=DF > --- > > =A0Documentation/powerpc/dts-bindings/fsl/mpc5200.txt | =A0 15 ++++++++++= ++++- > =A01 files changed, 14 insertions(+), 1 deletions(-) > > diff --git a/Documentation/powerpc/dts-bindings/fsl/mpc5200.txt b/Documen= tation/powerpc/dts-bindings/fsl/mpc5200.txt > index 8447fd7..1eecb06 100644 > --- a/Documentation/powerpc/dts-bindings/fsl/mpc5200.txt > +++ b/Documentation/powerpc/dts-bindings/fsl/mpc5200.txt > @@ -103,7 +103,20 @@ fsl,mpc5200-gpt nodes > =A0--------------------- > =A0On the mpc5200 and 5200b, GPT0 has a watchdog timer function. =A0If th= e board > =A0design supports the internal wdt, then the device node for GPT0 should > -include the empty property 'fsl,has-wdt'. > +include the empty property 'fsl,has-wdt'. =A0Note that this does not act= ivate > +the watchdog. =A0The timer will function as a GPT if the timer api is us= ed, and > +it will function as watchdog if the watchdog device is used. =A0The watc= hdog > +mode has priority over the gpt mode, i.e. if the watchdog is activated, = any > +gpt api call to this timer will fail with -EBUSY. > + > +If you add the property > + =A0 =A0 =A0 wdt,on-boot =3D ; > +GPT0 will be marked as in-use watchdog, i.e. blocking every gpt access t= o it. > +If n>0, the watchdog is started with a timeout of n seconds. =A0If n=3D0= , the > +configuration of the watchdog is not touched. =A0This is useful in two c= ases: > +- just mark GPT0 as watchdog, blocking gpt accesses, and configure it la= ter; > +- do not touch a configuration assigned by the boot loader which supervi= ses > + =A0the boot process itself. I'm not *totally* convinced on the usage model, but I just need some time to think about it. Give me a day or so and ping me again if you haven't heard from me. However, until a common WDT binding is defined, this property needs to be named something like "fsl,wdt-on-boot". Cheers, g. --=20 Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd.